Investigation of polynuclear Zr(IV) hydroxide complexes by nanoelectrospray mass-spectrometry combined with XAFS

Polynuclear species of zirconium in acidic aqueous solution are investigated by combining X-ray absorption spectroscopy (XAFS) and nanoelectrospray mass spectrometry (ESI-MS). Species distributions are measured between pH_C 0 and pH_C 3 for [Zr] = 1.5–10 mM. While the monomer remains a minor species, with increasing pH the degree of polymerization increases and the formation of tetramers, pentamers, octamers, and larger polymers is observed. The high resolution of the mass spectrometer permits the unambiguous determination of polynuclear zirconium hydroxide complexes by means of their isotopic patterns. The relative abundances of mononuclear and polynuclear species present simultaneously in solution are measured, even if one of the species contributes only 0.1% of the Zr concentration. For the first time it has been directly observed that the hydrolysis of polynuclear Zr species is a continuous process which leads to charge compensation through the sequential substitution of water molecules by hydroxide ligands until doubly charged polymers dominate at conditions (H⁺ and Zr concentrations) close to the solubility of Zr(OH)₄(am). The invasiveness of the electrospray process was minimized by using very mild declustering conditions, leaving the polynuclear species within a solvent shell of approximately 20 water molecules. Figure Schematic Diagram of Multiplexed Measurement of 9 Anti-Nuclear Antibodies Using the AtheNa Multilyte Assay     

Towards an efficient atomic frequency comb quantum memory

We present an efficient photon-echo experiment based on atomic frequency combs [Phys. Rev. A 79 (2009) 052329]. Echoes containing an energy of up to 35% of that of the input pulse are observed in a Pr³⁺-doped Y₂SiO₅ crystal. This material allows for the precise spectral holeburning needed to make a sharp and highly absorbing comb structure. We compare our results with a simple theoretical model with satisfactory agreement. Our results show that atomic frequency combs has the potential for high-efficiency storage of single photons as required in future long-distance communication based on quantum repeaters.     

Synchronous, dual-wavelength, injection-seeded amplification of 5-ns pulses in a flash-lamp-pumped Ti:sapphire laser

The outputs of two cw diode lasers are coupled into a flash-lamp-pumped Ti:sapphire laser cavity for regenerative amplification. Slices of each seed beam are simultaneously trapped in the cavity and amplified for approximately 33 round trips. The output is a 4.7-ns pulse, the total pulse energy is 110 mJ, and linewidths are only 50% greater than the Fourier-transform limit. The timing jitter between the pulses at the two wavelengths is less than +/-75 ps , and their relative energy is controlled by adjustment of the seed power of the cw diode lasers. Gain competition between the two frequencies does not lead to instabilities.     

Lifetime measurements in the Fe I spectrum using tunable dye laser excitation

Radiative lifetimes of single fine structure levels of the multiplets 3d⁶ 4s(a⁶ D)4p z⁵ D ⁰ and 3d⁷ (a⁴ F)4py ⁵F⁰ of the FeI spectrum were measured. The different levels were excited by a tunable dye laser which was pumped by a pulsed nitrogen laser. The exponential decay of the fluorescence was measured directly.     

The hyperfine structure of they 8 p-multiplet of 4f 7(8 S) 6s 6p in EuI

The hyperfine splitting constants of the 4f ⁷ 6s 6p y ⁸ P _7/2 level of Eul were determined using the level crossing method. These values and those for the hyperfine splittings of the other 4f ⁷ 6s 6p levels are compared to theoretical values calculated with eigenfunctions of Smith and Collins. For the quadrupole coupling constants a better agreement between theory and experiment is obtained if different 〈r ^?3〉 _p -parameters are assumed for 4f(⁸ S) 6s 6p(³ P) and for 4f ⁷(⁸ S) 6s 6p(¹ P).     

Die relative Isotopenlage des Os186

Using three different samples of Os¹⁹², Os¹⁹⁰ and Os¹⁸⁶ enriched to 98.68%, 95.46%, and 61.27%, respectively, the isotopic shiftsΔν(Os¹⁹²?Os¹⁹⁰) andΔν(Os¹⁹²?Os¹⁸⁶) have been measured in four Os I-lines with a recording Fabry-Perot spectrometer. The relative isotopic position of Os¹⁸⁶ has been found to be

$$\frac{{\Delta \nu (Os^{192} - Os^{186} )}}{{\Delta \nu (Os^{192} - Os^{190} )}} = 3.52 \pm 0.03.$$     

Experimente mit Erdalkaliatomen in metastabilen Zuständen

An atomic beam source for atoms in metastable states is described. The source was used to produce metastable Ca and Sr atoms in the³ P _0,1,2 and¹ D ₂ and Mg atoms in the³ P _0,1,2 states. The population of these levels was high enough (about 30% of the atoms were in the³ P levels and 3% in the¹ D ₂ level) so that zero field level crossing experiments could be performed at highly excited levels which were populated by an optical excitation starting from the metastable states. The lifetime results obtained for Ca areτ(4s 4d ³ D ₁)=(1.21±0.07)·10^?8sec,τ(4s 4f¹ F ₃)=(2.84±0.23)· 10^?8sec, andτ(3d 4p ¹ F ₃)=(6.15±0.62)·10^?8 sec. The three lifetimes have been evaluated using theg _J values forLS-coupling. The quoted uncertainties include the errors by a possible deviation fromLS-coupling.